Portable remote location measuring system

ABSTRACT

A portable system for measuring a condition, particularly temperature, and indicating this measurement at a remote location. A portable insulating and protective container adapted for use in extreme temperature environments, such as occasioned within a furnace or oven, houses a small transmitter. The transmitter is connected to a transducer responsive to the condition to produce a signal that is transmitted to a remote receiving and monitoring location.

United States Patent Stacey [451 Jan. 25, 1972 s41 PORTABLE REMOTELOCATION 2,8l8,732' 1/1958 Bennett ..73/362 MEASURING SYSTEM 2,992,1207/1961 Elsken ..340/208 X y 3,008,666 1 1/196] Kuck v ..325/1 13 X [72]Inventor: David S. Stacey, Carbondale, Colo. 3,158,027 1 l/ 1964 Kibler..340/224 X 3,298,430 1/1967 Kodaira ..219/388 X [73] i' 3,333,4768/1967 Hardy et a1 ..73/3e2 R [22] Filed: Jan. 21, 1969 PrimaryExaminerBernard A. Gilheany [21] Appl' 792395 Assistant Examiner-F. E.Bell Attorney-Campbell, Harris and ORourke [52] US. Cl "219/490 5 1] im.Cl. ..H05b1/02 1 1 ABSTRACT 0 Search A portable system for measuring acondition particularly 73/359 340/208 397/1 2 perature, and indicatingthis measurement at a remote loca- 220/17 165/75 tion. A portableinsulating and protective container adapted for use in extremetemperature environments, such as occa- [56] References and sionedwithin a furnace or oven, houses a small transmitter. UNITED STATESPATENTS The tr' msmitter is conneeted to a trensducerresponsive to thecondition to produce a signal that IS transmitted to a remote 1,323,52512/1919 Dutton ..219/40l X receiving and monitoring location. 1,958,5905/1934 Peirce ..219/40l 2,635,468 4/1953 Field et a1..

9 Claims, 8 Drawing Figures PATENTEU mas 1972 3.637985 saw-1 0F 4RECEIVER I RECORDER INVENTOR.

DAVID s. STACEY A TTOR/VEYS v PATENIEU JAH25 I972 SHEET 2 BF 4 INVENTOR.DAVID S. STACEY BY W kul2 PATENTED JAN25 1972 SHEEI 3 BF 4 INVENTOR.DAVID S. STACEY wwkmmyu A TTORIVE Y5 mmmm 3.637.985

sum nor 4,

PORTABLE REMOTE LOCATION MEASURING SYSTEM BACKGROUND OF THE INVENTION 1.Field of the Invention This invention relates to a remotely locatedcondition measuring system and particularly to a portable system for usein an oven to generate temperature indicative signals and to transmitthese signals. v

2. Description of the Prior Art It is often necessary to determine theexistence and magnitude of a condition at a remote location. This isparticularly true, for example, in the maintenance of temperatureconditions in glass production wherein glassware, such as containers,tubing, or glass sheets and the like, is formed at rela tively hightemperatures and is thereafter annealed or heattreated down to roomtemperatures. a

It is well recognized that the range of temperatures for optimumannealing of glassware is relatively small and, as annealing time isdecreased in the interest of manufacturing efficiency withoutsacrificing favorable physical and chemical properties of the glassproduct, temperature regulation becomes even more critical. Often, thetemperature of glassware within the oven, known as a lehr, must becontrolled within a tolerance of plus or minus 50 F. in order to achieveoptimum annealing; hence, it is important that the glassware temperaturebe closely monitored as the ware travels through the annealing lehr oroven. In this manner, better regulation of the temperature in the ovencan be achieved which results, of

course, in better regulation of glassware temperatures.

While apparatus for temperature measurement within an oven orfurnace,.including optical'or radiation pyrometers, electronicpyrometers and thermocouples, have heretofore been known and/orutilized, none of these devices have proved to be completely successful.A major problem with the optical pyrometer, which measures the intensityof radiation by an incandescent body, is that the hot gases contained inthe medium about the body interfere with the readings. As is well known,temperature responsive electronic devices, such as thermistors, are notpractical at the high temperatures encountered in the first stages of aglass-annealing process.

While the thermocouple overcomes many of the disadvantages of otherprior art devices, it has not proved to be completely successful due atleast partially to bulkiness and a requirement for associated usage ofunwieldly equipment, particularly where long oven usage wascontemplated. More specifically, if the thermocouple is to travel withthe ware riding on a belt through the annealing oven, wire conductorshave heretofore been necessary in order to conduct the electricalsignalfrom the thermocouple to a temperature meter or recorder outside theoven for prompt indication. Beside being cumbersome, the added effectiveresistance of the wires subjected to varying oven temperatures tended tointroduce errors which often made the obtained readings so inaccurate asto be unreliable.

The present invention is an improvement over such temperaturemeasurement systems of the prior art; yet, the invention permits the useof a relatively inexpensive sensor such as a calibrated thermocouple forthe measurement. The apparatus includes a portable transmitting unitwhich is impervious to contemplated adverse conditions to beencountered; also, the unit is small enough to travel through anannealing oven with the ware and requires no associated cumbersomeequipment or connecting wires to generate a condition indicating signaland conduct the same outside the oven for utilization. I

The portable unit includes a transmitter responsive to the magnitude ofthe signal from a transducer, such as a thermocouple utilized in themeasurement of temperature, to radiate signals suitable for immediateconversion outside of the oven to a temperature indicator thataccurately reflects the temperature sensed within the oven. The unitfurther includes, in order to protect the electrical components of thetransmitter,.an insulating container adapted to receive the transmitterfor protecting it against high temperatures encountered within the oven.

2 SUMMARY OF THE INVENTION The invention enables accurate and remotemonitoring of a condition. It is particularly useful'for measurement ofextreme temperature conditions such as may be encountered in aglassannealing oven. Further, the invention enables accurate temperaturemeasurement in changing environments which are displaced one from theother and from the monitoring location.

Thus, it is an object of the present invention to provide a I novelportable sensing system for the indication of a condition existing at aremote location from the condition monitoring location.

It is another object of the invention to provide a wireless sensingsystem for the measurement of a condition and the indication of thecondition at a remote location.

It is a further object of the invention to provide aportable measuringapparatus which may be operated in a high temperature environmentsuch-as occasioned within an oven or furnace.

A further object of the invention is to provide a transmitting unitoperative within a' high temperature environment to produce and transmitsignals indicative of a condition such as temperature within theenvironment.

A further object of the present invention is to provide, a portabletemperature sensing system having a calibrated thermocouple transducerresponsive to temperature, and a temperature compensation network toautomatically produce a signal to compensate for the change in thereference junction temperature of the thermocouple from the referencejunction calibration temperature thereof.

Another object of the invention is to .provide an insulating containerfor housing and protecting a transmitter from extreme environmentalconditions outside the container.

It is a further object of the invention to provide a portabletemperature sensing system having the contained transmitter sensingsystem having the contained transmitter responsive to a a transducersignal, and an adjustable temperature compensation network to provide asignal to compensate for parameter changes of the transmitter due totemperature changes thereof from a predetermined reference temperature.

These and other objects and advantageswill be apparent to thoseskilledin the art from the following description of a preferred embodiment ofthe invention as shown in the accompanying drawings.

BRIEF-DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of themeasuring'apparatus of the invention shown in conjunction with anannealing lehr to sense temperatures within said lehr;

FIG. 2 is a perspective view of the portable measuring apparatus shownin FIG. 1;

FIG. 3 is an exploded perspective view of the transmitting unit with aportion cutaway for illustrative purposes;

FIG. 4 is a side sectional view of the container taken along the lines4-4 of FIG. 2;

FIG. 5 is a view similar to FIG. 4 but taken along the. lines 5-5 ofFIG. 2;

FIG. 6 is a schematic circuit diagram of the transmitter shown in FIG.3; and

FIGS. 7a and 7b are a circuit and graph, respectively, to il- Iustratethe manner of calibration of the thermocouplel DESCRIPTION OF THEPREFERRED EMBODIMENT Referring to FIG. 1, a preferred embodiment of themeasurement apparatus 8 of the system for use in a high-temperatureenvironment is shown positioned to travel through an oven or furnace '10on a conveyor belt 12 in the direction as indicated by the arrow.Measuring apparatus 8 includes a transmitting unit 14 (as shown in FIG.3) positioned within an insulating container 15 of a material such assteel, for example, and is provided to generatea signal indicative oftemperature, such as the temperature of one of the glass jars l6.Measuring apparatus 8 and jars 16 are positioned on the conveyor belt 12so as to permit travel through the oven at a fixed distance one from theother. Measurement apparatus 8 includes, as shown best in FIGS. 2 and 3,the insulating container 15 having a base member shown in the drawingsas a metal cylindrical can and a metal cover member 22 also cylindricalin shape and adapted to tightly fit onto the can 20.

A thermocouple 24 is attached to the surface of a jar 16 by anyconventional means such as by a tape or by a suitabletemperature-resistant bonding adhesive. The temperature of theparticular jar 16 is sensed by the thermocouple 24 and the correspondingsignal conducted through wires 25 to the transmitting unit 14. Thetemperature signal is thereupon processed as more fully hereinafterdescribed with reference to FIG. 6 and a corresponding radiant energysignal is transmitted out of the oven 10 to a receiver 26, preferablylocated outside the oven, the output signal from which receiver may beimmediately indicated by a temperature meter (not shown) and/orpermanently recorded on a time-temperature recorder 28.

Although a thermocouple for producing a signal cor responding totemperature is shown, it should be readily apparent that othertransducers might be substituted to detect other conditions; forexample, a stain gage to detect thermal expansion or contraction of anarticle such as one of the jars 16. In addition, it is to be appreciatedthat the transmitted signal could be an environmental signal within theoven in which case the transducer may be detached from any articletraveling through an oven 10. I

Referring particularly to FIG. 3, there is shown a disassembled cutawayportion of the measurement apparatus 8. TI-Ie can 20 is partially filledwith an insulating'powder up to a refractory ring-shaped plate 32 andabout a cylindrical cup 34 concentrically positioned within can 20 andheld in place by the plate 32 and generally by the powder 30.Transmitter 14 is received and confined within a cavity 36 defined bythe cup 34. The electrical elements 'of the transmitter are received ina casing, or can, and are mounted on a rectangular circuit block 37attached at one end to a base 38. In an embodiment constructed inaccordance with the invention, can 35 and base 38 were also made ofsteel. Base 38 is essentially disc-shaped with a central portion closingthe interior of the can 35 and having a shoulder 39 terminating inperipheral flange 40. Shoulder 39 extends downwardly from flange 40 andhas an O-ring 41 mounted thereon to seal the can 35. Flange 40, whichhas a plurality of holes 41 when transmitter 14 is received within thecavity 36 so as to longitudinally position the transmitter within thecup 34.

The cylindrical casing, or can, 35 has a diameter smaller than the innerdiameter of the cup 34 so as to define a space between respective wallsthereof when the transmitter 14 is positioned within cavity 36, whichspace opens to holes 43 in flange 40. The central portion of base 38 hasthree openings therein to receive insulated terminals 44 and 46, and aground terminal 48, which terminals are connected with the electricalcomponents within the casing 35 as more fully hereinafter described withreference to FIG. 6.

Referring to FIGS. 3, 4, and 5, the cover member 22 has an outercylindrical wall 49 slightly larger in diameter than can 20 so that thelower portion of wall 49 receives the upper portion of the can 20therebetween. Cover member 22 is also filled with the insulating powder30 but is contained by a refractory ring-shaped plate 50 positionedinwardly from the lower end and having a shoulder 52 at the inner wallof the cover member. Cover member 22 is provided with a longitudinallyextending tube 54 opening at one end to a laterally extending chimneyhood 56 suitably welded to the top of the cover member 22, and openingat the other end through plate 50 to the interior of can 20. A nut 58 isthreadably engaged on the end of tube 54 adjacent to plate 50 to supportthe plate. As shown in FIG. 5, the passageway formed by the tube 54extending through the cover 22 is offset from center; nevertheless, itshould be apparent that exact positioning of the tube is not critical solong as tube 54 communicates with cup 34. Removal of the cover 22 fromcan 20 is facilitated by bars, or handles, 57 and 59 attached to thecover and can, respectively.

A ring 60 of a size sufficient to substantially bridge the area betweenthe sidewall of can 20 and cup 34 is bonded to the plate 50 in order tofacilitate positioning of cover 22. Thus, when the cover is in positionon can 20, a cavity 62 is formed providing a passageway between tube 54and the holes 43 in flange 40 and the passageway through tube 54. Sincethe cylindrical casing 35 of transmitter 14 has a diameter smaller thanthe diameter of the cup 34, a liquid may be contained within the cup 34about and under the casing 35. Therefore, a liquid heated to its boilingpoint in the oven or furnace environment may escape in vapor formthrough holes 43 into the cavity 62 and through the passageway formed bytube 54 and out to the oven or furnace. The vapor or steam may alsocirculate in the cavity 62 between the ring 60 and plate 32.

The provision for the containment of a liquid, such as water, about thecasing 35 insures that when heat is conducted through the thick layer ofinsulating powder 30 the casing 35 will reach at a maximum temperatureonly the boiling point temperature of the liquid contained. Of course,after the liquid is depleted, the casing 35 could reach a highertemperature and, hence, if the transmitter utilized cannot tolerateelevated temperature, then a sufficient supply of liquid must be assuredfor the operation time contemplated. If the transmitter can withstandelevated temperatures, then, of course, it is not mandatory that aliquid be used, although it might prove ad vantageous for more unifonnresults even in this latter case.

It is obvious that the general dimensions of the measurement apparatus8, and more specifically the thickness of the layer of powder 30, andwidth of cup 34 may be varied depending on contemplated usage tomaintain suitable transmitter temperature. The embodiment shown wasbuilt and tested for use at temperatures exceeding l,000 F. for at least15 minutes, and found to be satisfactory for use in conjunction with aglass annealing process.

The wires 25 of the thermocouples 24 attached to one of the glass jars16 may be inserted through chimney hood 56, through tube 54, andconnected to the insulated input terminal 44 and ground terminal 48 ofthe transmitter. Further,

an antenna 64 from the transmitter 14 may be connected to the terminal46 and also extend in the assembled position of the measurementapparatus 8 through the tube 54 and out of the cover member 22. Sincethe wave propagation distance out of the annealing oven 10 from theapparatus 8 is generally relatively short, suitable transmission may beeffected, for ex: ample, by positioning a simple wire antenna outsidethe cover member 22. 1 i

Referring to FIG. 6, transmitter 14 receives a direct current inputsignal from thermocouple24 through wires 25 which signal is indicativeof the magnitude of the temperature at the surface of the particularglass jar 16 to which the thermocou ple is secured. The thermocouple 24is of a conventional type, such as iron-constantan, suitable for useover wide temperature ranges.

The thermocouple 24 is attached to the surface of the glass- I05b.Preferably, the metal conductors 105 of the circuit are copper.Therefore, a thermoelectric effect may also be developed across eachjunction 104 although the junctions are at substantially the sametemperature.

The thermocouple having effectively three junctions may be calibrated inconventional manner as more particularly illusmaintained equal to eachother but above the temperature at which the reference junctions aremaintained during calibration (the new temperature being indicated byT,), the indicated reading upon measurement is reduced and must becorrected. The correction is simply the voltage produced when thereference junctions are at temperature T and the measuring junction attemperature T,. The thermocouple relation may be expressed as follows:

where as already explained, T is the reference junction calibrationtemperature, T, is a new reference junction temperature, and T is themeasuring junction temperature.

In the present invention there is accordingly provided a sensistor 106of conventional type and having a predetermined resistance changecharacteristic as a function of temperature to compensate fortemperature variations of the reference junction 104 from thecalibration temperature. Sensistor 106 is connected in a voltagedividing compensation network 110 so as to compensate the input signalby a voltage which varies with temperature approximately the same as thevoltage variance across junction 102 as a function of temperaturedifference from the reference junction temperature. In this manner, acorrected emf is produced which includes T to automatically compensatefor the signal change due to the actual reference junction temperaturebeing different from the reference junction temperature at which thethermocouple 24 is calibrated. As an example, if the reference junctions104 were at the boiling point of water and the measuring junction 102was at a higher temperature, the compensation voltage to be added to athermocouple previously calibrated with the reference junction at 32 F.and to be produced by sensistor 106 would be the voltage produced by thethermocouple when the reference junctions 104 are at 32 F. and themeasuring junction 102 is at the boiling point of water.

If water is used as the liquid in tube 34 about the transmitter 14, thetemperature of the reference junctions 104a and 104b at terminals 44 and48, respectively, will often be at substantially the boiling point ofthe water after sustained travel of unit 14 through the high temperatureoven whereupon the steam fills cavity 62 adjacent the tenninals and 48,and which steam escapes through tube 54. I

The uncompensated thermocouple signal from measuring junction 102 isconducted between junctions 104a and 104b at the input terminal 44 andground terminal 48, respectively, to the compensation network 110. Thenetwork 110 connected to terminal 44 includes the sensistor 106connected to the positive electrode of a battery 112, and a resistor 114connected to the negative electrode of battery 112. A resistor 116 isconnected between sensistor 106 and battery 112 to a potentiometer 118serially connected to a resistor 120 leading also to the negativeelectrode of battery 112. A switch 122 is further connected to thenegative electrode of battery 112 and is open at position A as shown ormay be closed in position B with the wiper arm of a potentiometer 124,the opposite end of which potentiometer is connected between theresistors 116 and 118 and to a resistor 119. I

The sensistor 106 and resistor 116 have a substantially low resistancein comparison to the other resistors of the compensation network and maybe considered as the only path of network 110 conductive of the signalfrom thermocouple 24. It is readily apparent that the direct currentvoltage drop across sensistor 106 at a given temperature and acrossresistor 116 may be initially set by the adjustment of the resistancevalues of potentiometer 118 and/or potentiometer 124 when switch 122 isin position B. Potentiometer 124 may be adjusted according to thedifferent ranges of operation of thermocouple 24. The voltage dropacross sensistor 106 thereafter is a function of temperaturecorresponding to the compensation voltage.

The voltage-dividing network 110 may be utilized also to compensate forthe approximated change in the thermocouple signal as processed due tominor changes or circuit parameters incurred with increased temperatureof the transmitter 14. More specifically, the resistance ofpotentiometer 118 may be varied to change the current from battery 112through one leg having resistors 116, 118, and 120, with respect to theother leg in parallel with the one leg, and including sensistor 106 andresistor 114. Further, when switch 122 is in position B, thepotentiometer 124 is in parallel with potentiometer 118 and resistor120. The relative resistance of the current paths from battery 112 maythus be adjusted so as to further regulate the current through and,therefore, the initial voltage drop across resistor 116 with respect tothe current through and the voltage drop across sensistor 106.

The thermocouple signal, as particularly compensated in accordance withthe reference junction temperature during use from the referencejunction calibration temperature, is conducted through resistor 119 toan inverting input of a direct current operational amplifier 120 ofconventional type, such as the am 702 Monolithic Operational Amplifier"particularly suitable for amplification of transducer outputs, and soldby Fairchild Semiconductor (a Division of Fairchild Camera), 313Fairchild Drive, Mountain View, California.

The output of amplifier 120, conducted through aZener diode 122 whichestablishes a reference voltage level, controls the current through aPNP-type resistor 124. A unijunction transistor I26 produces anoscillating signal at a frequency determined by the charging current toa capacitor 128. The output of unijunction transistor 126 is'an audiosignal .of frequency proportional to the voltage at the collector oftransistor 124. The current in resistor 158 is accurately proportionalto the frequency and is fed back to the noninverting input of amplifier120'to form a highly stable voltage-tofrequency converter. A secondunijunction transistor 130 is provided in order to compensate for directcurrent drifts of the unijunction transistor 126. v

The audiofrequency signal, in the form of a pulse of short duration, iscoupled through a direct current blocking capacitor 132 to a pulseshaper which may be of monostable multivibrator type which includesNPN-transistor l34 and PNP- transistor 136. The output from the pulseshaper is a series of stretched" pulses in phase and frequency with theaudio signal from unijunction transistor 126. An oscillator, whichincludes transistor 137, produces a radiofrequency carrier signal whichis amplitude modulated by the pulses at the audio signal frequency. Thefeedback path of the oscillator includes an inductor of a parallel tankcircuit 138 which is tapped and connected to the base of transistor 137and is also magnetically coupled to an inductor connected between thebase of transistor 137 and ground. Upon conduction of transistor 137,the current induced in inductor 140 in one direction drives the basemore negative and below cutoff rendering the transistor 137nonconductive. The breakdown of the field about the inductor in tank 138induces a current in the opposite direction in inductor 140 therebyimmediately rendering the base of transistor 137 positive beyond cutoff.The cycle repeats and transistor 137 sustains oscillation, and asmodulated by the audio signal from transistor 136 the carrier signal isradiated from the antenna 64 magnetically coupled to the inductor of thetank circuit 138.

With good conduction in a lehr oven which typically may measure about 7feet wide, the oven will act as a waveguide and cut 06' spurious signalswith a half wavelength longer than the width of the oven. The cutoffsignals would be at a frequency of approximately 70 ml./s. and less inthe typical lehr oven mentioned. However, operation with carrier signalshaving a greater half wavelength than the width of the oven may often bedesirable. It has been found suitable in this instance to feed a pickupwire (not shown) through the oven 10 and to anchor this wire to thesides of the oven.

The power or supply voltage source for the transmitting unit mounted onthe circuit board block 37 contained within the cylindrical casing 35and are of a type such as those known as mercury batteries which havebeen found suitable for operation at temperatures in the area of boilingpoint of water. Further, silicon-type semiconductors were utilized inthe transmitter for operation at such temperatures.

For purposes of example, the following lists the identifying typesand/or parameters of elements, in addition to those already mentioned,utilized in a particular tested embodiment of l the transmitter 14:

Resistors Parameter Capacitors Parameter (ohms) (flrads) 106(sensitor) II28 I0" 114 20.5 K 132 sue- I I6 I00 I63 I0 IIB (potent.) K I64 I0" I I9576 I65 10" I 20 K I66 l0 124(potent.) l7.2 K I67 10" I50 649 168 I0"I51 I20 169 I0" I52 2.57 K I70 5(10') I53 L3 K "I 10-" I54 4.25 K I554.75 K Diodes Type 156 I00 I57 649 I22 IN755 I58 I00 I75. FA8004 I59 240I7II IN3605 I60 7.5 K I6I [5.8 K Transistors I62 6L9 I24 2N363fl I262N2647 I30 2N2647 I34 2N3S65 I36 2N3638 I37 2N364l Although only oneembodiment of the invention has been illustrated and described, it isanticipated that various changes and modifications will be apparent tothoseskilled in the art, and that such may be made without departingfrom the scope of the invention as defined by the following claims.

Iclaim: I

I. A system for monitoring a condition within an oven, the conditionexisting within the oven at a location remote from the monitoringlocation, the system comprising:

a transducer for producing a signal indicative of the condition sensedwithin an oven;

means for transmitting an electromagnetic energy signal corresponding tothe transducer signal;

an insulated container for receiving said transmitting means, saidinsulated container including liquid means and vapor escape means forpreventing the temperature within said container from rising beyond apredetermined temperature while in an oven;

means for receiving the transmitted signal; and

means for converting the received signals to indicate the conditionsensed within the oven by said transducer.

2. The system as defined in claim 1 wherein:

said container has a cavity larger than said transmitting means and intowhich said cavity said transmitting means is received;

wherein said liquid means for preventing the temperature within saidcavity from rising beyond a predetermined temperature is contained inthe cavity about said transmitting means, and wherein said vapor escapemeans includes a passageway in said container and opening externally ofsaid container from said cavity so that the liquid upon vaporizationbeing able to escape through the .14 is supplied from batteries 146 and148 which are also 5 passageway so as to maintain the immediateenvironment of said transmitting means at substantially the liquidtemperature.

3. The system as defined in claim I wherein the transducer includes:

a calibrated thermocouple having a measuring junction and at least onereference junction; and

wherein the transmitting means includes:

an oscillator for producing a carrier signal;

compensating means including a sensistor for providing a signal tooffset any error in the signal from the thermocouple due to temperaturedifference of the reference junction from a predetermined calibrationtemperature;

converting means for producing a pulse signal train having a frequencyindicative of the amplitude of the compensated thermocouple signal;

an antenna coupled to said oscillator; and

means for insulating said converting means, said compensating means,said oscillator, and the reference junction of said thermocouple;

whereby the carrier signal may be modulated by the pulse signal trainfrom said converting means and radiated by said antenna from within theoven to said receiving means.

4. A system for measuring a condition in an oven, the system comprising:a transducer for producing a signal indicative of the condition; anelectronic unit for receiving the signal from said transducer; and aninsulating container for the electronic unit including,

a base member,

thermal insulating means within said base member and defining a cavitywhich receives said electronic unit, said thermal-insulating meansdefining said cavity receiving liquid to surround said electronic unitreceived in said cavity, said container having vapor escape means so asto maintain the immediate electronic unit environment substantially atthe liquid temperature; and

a cover member removably mated with said base member,

other thermal-insulating means within said cover member,

one of said thermal-insulating means defining a passageway extendingfrom the cavity through the wall of the respective member,

whereby the transducer may be connected to the electronic unit throughthe passageway.

5. A system for monitoring the temperature of an article of manufacturetraveling through a furnace, the system comprismg:

a transducer within the furnace to travel with the article for producinga signal corresponding to the temperature of the article at successivelocations in the furnace;

a transmitter for transmitting an electromagnetic energy signalcorresponding to the transducer signal;

' a portable insulated container to travel with the article, saidcontainer receiving and protecting said transmitter from adversetemperature conditions existing within the furnace;

said insulated container containing liquid about the transmitter andhaving a passageway extending from within and through said container,

whereby the liquid upon vaporization may escape from said containerthrough the passageway so as to maintain the transmitter temperature atsubstantially the liquid temperature;

means for receiving the transmitted signals;

whereby the received signals are indicative of the temperature sensed bythe transducer at successive locations within the furnace.

6. A system for monitoring an environmental condition at successivelocations within an oven, the successive locations being remote r m themonitoring location, the system comprising:

a transducer for producing a signal corresponding to the condition;

whereby the transmitter temperature may be-maintained at substantiallythe liquid temperature transmitter operation within the furnace;

means for moving said transducer, transmitter and container through theoven; and

means for receiving the transmitted signals;

whereby the transmitted signal may be received outside the oven from theremote locations of the sensed environmental c nd t n,- a a v r 7. Amethod of protecting a transmittertravelingthrough an oven, the stepscomprising:

sealing the transmitter in a liquidproof container;

immersing the sealed transmitter in a contained liquid medienclosing thesealed transmitter in the contained liquid medium within an insulatingcontainer; and

conducting the contained liquid in vapor form out of the insulatingcontainer.

to pennit efficient 8. A method of maintaining a reference junction of athermocouple transducer traveling through a heat treating oven below apredetermined temperature within the oven, the steps comprising:

positioning the reference junction of the themiocouple in a liquidenvironment;

insulating the reference junction of the thennocouple and the liquidenvironment; and

conducting the contained liquid in vapor form out of the insulatingcontainer;

whereby the reference junction may be substantially maintained below thepredetermined temperaturecorresponding to the boiling point temperatureof the liquid contained.

9. An assembly for sensing a condition within an oven comprising: aninsulated container defining therein a cavity of predetermined size;sensing means for producing a signal indicative of the condition sensedwithin the oven, at least a portion of said sensing means beingpositioned within said cavity, said portion being smaller in size thansaid cavity; and a liquid contained within said cavity and vapor escapemeans for preventing the temperature within said cavity from risingbeyond a predetermined temperature.

' a s s s a

1. A system for monitoring a condition within an oven, the conditionexisting within the oven at a location remote from the monitoringlocation, the system comprising: a transducer for producing a signalindicative of the condition sensed within an oven; means fortransmitting an electromagnetic energy signal corresponding to thetransducer signal; an insulated container for receiving saidtransmitting means, said insulated container including liquid and vaporescape means for preventing the temperature within said container fromrising beyond a predetermined temperature while in an oven; means forreceiving the transmitted signal; and means for converting the receivedsignals to indicate the condition sensed within the oven by saidtransducer.
 2. The system as defined in claim 1 wherein: said containerhas a cavity larger than said transmitting means and into which saidcavity said transmitting means is received; wherein said liquid meansfor preventing the temperature within said cavity from rising beyond apredetermined temperature is contained in the cavity about saidtransmitting means, and wherein said vapor escape means includes apassageway in said container and opening externally of said containerfrom said cavity so that the liquid upon vaporization being able toescape through the passageway so as to maintain the immediateenvironment of said transmitting means at substantially the liquidtemperature.
 3. The system as defined in claim 1 wherein the transducerincludes: a calibrated thermocouple having a measuring junction and atleast one reference junction; and wherein the transmitting meansincludes: an oscillator for producing a carrier signal; compensatingmeans including a sensistor for providing a signal to offset any errorin the signal from the thermocouple duE to temperature difference of thereference junction from a predetermined calibration temperature;converting means for producing a pulse signal train having a frequencyindicative of the amplitude of the compensated thermocouple signal; anantenna coupled to said oscillator; and means for insulating saidconverting means, said compensating means, said oscillator, and thereference junction of said thermocouple; whereby the carrier signal maybe modulated by the pulse signal train from said converting means andradiated by said antenna from within the oven to said receiving means.4. A system for measuring a condition in an oven, the system comprising:a transducer for producing a signal indicative of the condition; anelectronic unit for receiving the signal from said transducer; and aninsulating container for the electronic unit including, a base member,thermal insulating means within said base member and defining a cavitywhich receives said electronic unit, said thermal-insulating meansdefining said cavity receiving liquid to surround said electronic unitreceived in said cavity, said container having vapor escape means so asto maintain the immediate electronic unit environment substantially atthe liquid temperature; and a cover member removably mated with saidbase member, other thermal-insulating means within said cover member,one of said thermal-insulating means defining a passageway extendingfrom the cavity through the wall of the respective member, whereby thetransducer may be connected to the electronic unit through thepassageway.
 5. A system for monitoring the temperature of an article ofmanufacture traveling through a furnace, the system comprising: atransducer within the furnace to travel with the article for producing asignal corresponding to the temperature of the article at successivelocations in the furnace; a transmitter for transmitting anelectromagnetic energy signal corresponding to the transducer signal; aportable insulated container to travel with the article, said containerreceiving and protecting said transmitter from adverse temperatureconditions existing within the furnace; said insulated containercontaining liquid about the transmitter and having a passagewayextending from within and through said container, whereby the liquidupon vaporization may escape from said container through the passagewayso as to maintain the transmitter temperature at substantially theliquid temperature; means for receiving the transmitted signals; wherebythe received signals are indicative of the temperature sensed by thetransducer at successive locations within the furnace.
 6. A system formonitoring an environmental condition at successive locations within anoven, the successive locations being remote from the monitoringlocation, the system comprising: a transducer for producing a signalcorresponding to the condition; a transmitter for transmitting anelectromagnetic energy signal corresponding to the transducer signal; aportable insulated container receiving the transmitter, said containerhaving a passageway extending from within and through said container,and said container containing liquid about said transmitter; whereby thetransmitter temperature may be maintained at substantially the liquidtemperature to permit efficient transmitter operation within thefurnace; means for moving said transducer, transmitter and containerthrough the oven; and means for receiving the transmitted signals;whereby the transmitted signal may be received outside the oven from theremote locations of the sensed environmental condition.
 7. A method ofprotecting a transmitter traveling through an oven, the stepscomprising: sealing the transmitter in a liquidproof container;immersing the sealed transmitter in a contained liquid medium; enclosingthe sealed transmitter in the contained liquid medium withIn aninsulating container; and conducting the contained liquid in vapor formout of the insulating container.
 8. A method of maintaining a referencejunction of a thermocouple transducer traveling through a heat treatingoven below a predetermined temperature within the oven, the stepscomprising: positioning the reference junction of the thermocouple in aliquid environment; insulating the reference junction of thethermocouple and the liquid environment; and conducting the containedliquid in vapor form out of the insulating container; whereby thereference junction may be substantially maintained below thepredetermined temperature corresponding to the boiling point temperatureof the liquid contained.
 9. An assembly for sensing a condition withinan oven comprising: an insulated container defining therein a cavity ofpredetermined size; sensing means for producing a signal indicative ofthe condition sensed within the oven, at least a portion of said sensingmeans being positioned within said cavity, said portion being smaller insize than said cavity; and a liquid contained within said cavity andvapor escape means for preventing the temperature within said cavityfrom rising beyond a predetermined temperature.